"Frot" (short for frottage) or "phrot" (alternate spelling) among homosexual men tends to imply genital rubbing in a conventional private context, the female equivalent is sometimes referred to as tribadism.
As with most other sexual practices, frottage with a non-consenting person is regarded as a form of sexual assault in most jurisdictions. A widely-practiced form of frotteurism is inter-crural intercourse.